296 lines
10 KiB
ReStructuredText
296 lines
10 KiB
ReStructuredText
.. _howtorun:
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How to run Tezos
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================
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In this section we discuss how to take part in the protocol that runs
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the network.
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There are two main ways to participate in the consensus, delegating
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your coins and running a delegate.
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To learn more about the protocol refer to :ref:`this section <proof-of-stake>`.
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Delegating your coins
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---------------------
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If you don't want to deal with the complexity of running your own
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delegate, you can always take part in the protocol by delegating your
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coins to one.
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Implicit accounts cannot have a delegate, so the first step is to
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originate an account, transfer your tezzies there and set a delegate.
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Notice that an originated account is a special case of a contract
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without code, so it is still necessary to pay for its small storage
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(see `originated_account`).
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::
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tezos-client originate account alice_del for alice \
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transfering 1000 from alice \
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--delegate bob
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As done before, we originate a contract *alice_del* with manager
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*alice* and we fund it with 1kꜩ.
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The interesting part is setting the delegate to *bob*, when
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originating a contract the delegate is not set by default.
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If you already own contracts that are delegatable you can change
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the delegate with the command ``set delegate``.
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Notice that only implicit accounts can be delegates, so your delegate
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must by a *tz1* address.
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Funds in implicit accounts which are not registered as delegates
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do not participate in baking.
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Running a delegate
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------------------
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A delegate is responsible for baking blocks, endorsing blocks and
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accusing other delegates in case their try to double bake or double
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endorse.
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In the network, rights for baking and endorsing are randomly assigned
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to delegates proportionally to the number of rolls they have been
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delegated.
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A roll is just a block of 10kꜩ and all computations with rolls are
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rounded to the nearest lower integer e.g. if you have 16kꜩ it amounts
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to 1 roll.
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When you obtain coins from :ref:`the faucet<faucet>`, if you
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are lucky to obtain more than one roll, you can register a delegate
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using this identity.
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Otherwise, you need to ask the faucet for more accounts, originate an
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account for each one and delegate them to the first.
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Deposits and over-delegation
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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When baking or endorsing a block, a *security deposit* (or *bond*) is
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frozen for ``preserved_cycles`` cycles from the account of the
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delegate.
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Hence a delegate must have enough funds to be able to pay security
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deposits for all the blocks it can potentially bake/endorse during
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``preserved_cycles``.
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The current deposits are *512ꜩ* for baked block and *64ꜩ* for
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endorsement.
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Note that being delegated coins doesn't mean that a delegate can spend
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them, they only add up to its rolls count while all the deposits must
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come from the delegate's account.
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If a delegate runs out of funds to deposit it won't be able to bake or
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endorse, other than being a missed opportunity for them this has also
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negative consequences on the network.
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Missing baking slots slows the network, as it is necessary to wait one
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minute for the baker at priority 2 to bake, while missing endorsements
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reduce the fitness of the chain, making it more susceptible to forks.
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Running out of funds can happen if a delegate is *over-delegated*,
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that is if the amount of rolls it was delegate is disproportionate
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with respect to its available funds.
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It is the responsibility of every delegator to make sure a delegate is
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not already over-delegated (a delegate cannot refuse a delegation) and
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each delegate should plan carefully its deposits.
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.. _expected_rights:
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Expected rights, deposits and rewards
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Let's assume we have 1 roll, we want to estimate our chances to bake
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or endorse in order to prepare the funds for our deposits.
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Our chances depend on how many rolls are currently active in the
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network, once we know that we can estimate how many blocks and
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endorsements we could be assigned in a cycle.
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The number of active rolls can be computed with two RPCs, first we
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list all the active delegates with ``delegates?active``, then we sum
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all their ``stacking_balance`` and we simply divide by the size of a
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roll, 10kꜩ.
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At the time of writing, on Betanet the number of active rolls is ~30k
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so for each block we know that the chance that we get selected for
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baking is ``1/30k`` while for endorsing is 32 times that.
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Given that every draw is with replacement, the distribution that
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describes our chances of being selected is the binomial with
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probability of success ``p=1/30k``.
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The distribution has another parameter ``n`` for the number of times
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we draw, in our case in a cycle the draws for baking are ``n_b =
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4096`` while for endorsing are ``n_e = 4096 * 32``.
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Moreover we could extend ``n`` to cover ``preserved_cycles = 5``.
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Once we have ``p`` and ``n``, the expected number of times that we
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might get selected is ``p * n`` (the mean of the distribution).
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Over many cycles our chances will fall around the mean, in some cycles
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we will unlucky get less rights, but in some cycles we might get lucky
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and be assigned more rights!
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Clearly we would like to plan ahead and have enough deposits to cover
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also the "lucky" cycles so we need to compute a sort of "maximum"
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number of rights that is safe for `most cases`.
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We can compute this maximum using the inverse of Cumulative
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Distribution Function of the Binomial where `most cases` is a value of
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confidence that we can put to 95%.
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There a simple `Python
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script<https://gitlab.com/paracetamolo/utils/blob/master/estimated-rights.py>`_
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that does the computation for us and returns the deposits and rewards,
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expected and maximum, for a cycle and for `preserved_cycles`.
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::
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prob success 3.333333e-05
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confidence 0.95
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----------one-cycle--------------------
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blocks
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mean 0.14
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max 1.00
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endorsements
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mean 4.37
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max 8.00
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deposits
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mean 69.91 + 279.62
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max 512.00 + 512.00
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rewards
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mean 2.18 + 8.74
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max 16.00 + 16.00
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----------preserved-cycles-------------
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blocks
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mean 0.68
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max 2.00
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endorsements
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mean 21.85
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max 30.00
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deposits
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mean 349.53 + 1398.10
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max 1024.00 + 1920.00
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rewards
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mean 10.92 + 43.69
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max 32.00 + 60.00
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As a rule of thumb if we want to have a very high confidence that we
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won't miss any opportunity we should have around ~3kꜩ for deposits,
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on the other hand the expected returns will probably be around ~10ꜩ per cycle.
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After ``preserved_cycles``, not only the delegate takes back control of
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its frozen deposits but it also receives the rewards for its hard work
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which amount to 16ꜩ to bake a block and ``ꜩ2 / <block_priority>`` for
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endorsing a block.
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Additionally a baker also receives the fees of the operations it
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included in its blocks.
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While fees are unfrozen after ``preserved_cycles`` like deposits and
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rewards, they participate in the staking balance of the delegate
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immediately after the block has been baked.
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Register and check your rights
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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In order to run a delegate you first need to register as one using
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your implicit account:
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::
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tezos-client register key bob as delegate
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Once registered, you need to wait ``preserved_cycles + 2 = 7`` cycles
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for your rights to be considered.
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There is a simple rpc that can be used to check your rights for every
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cycle, up to 5 cycles in the future.
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::
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tezos-client rpc get /chains/main/blocks/head/helpers/baking_rights\?cycle=300\&delegate=tz1_xxxxxxxxxxx\&max_priority=2
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Sometimes a delegate skips its turn so it is worth considering also
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baking rights at priority 2 like in the example above.
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There is no priority for endorsements, every missed endorsement is
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lost.
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Inactive delegates
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~~~~~~~~~~~~~~~~~~
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If a delegate doesn't show any sign of activity for `preserved_cycles`
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it is marked **inactive** and its rights are removed.
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This mechanism is important to remove inactive delegates and reallocate
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their rights to the active ones so that the network is always working
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smoothly.
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Normally even a baker with one single roll should perform enough
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operations during 5 cycles to remain active.
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If for some reason you delegate is marked inactive you can reactivate
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it simply by re-registering again like above.
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Baker
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~~~~~
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The baker is a daemon that once connected to an account, computes the
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baking rights for that account, collects transactions from the mempool
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and bakes a block.
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Note that the baker is the only program that needs direct access to
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the node data directory for performance reasons.
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Let's launch the daemon pointing to the standard node directory and
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baking for user *bob*:
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::
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tezos-baker-alpha run with local node ~/.tezos-node bob
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Endorser
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~~~~~~~~
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The endorser is a daemon that once connected to an account, computes
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the endorsing rights for that account and, upon reception of a new
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block, verifies the validity of the block and emits an endorsement
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operation.
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It can endorse for a specific account or if omitted it endorses for
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all accounts.
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::
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tezos-endorser-alpha run
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Accuser
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~~~~~~~
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The accuser is a daemon that monitors all blocks received on all
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chains and looks for:
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* bakers who signed two blocks at the same level
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* endorsers who injected more than one endorsement operation for the
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same baking slot (more details :ref:`here<proof-of-stake>`)
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Upon finding such irregularity, it will emit respectively a
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double-baking or double-endorsing denunciation operation, which will
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cause the offender to loose its security deposit.
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::
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tezos-accuser-alpha run
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Remember that having two bakers or endorsers running connected to the
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same account could lead to double baking/endorsing and the loss of all
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your bonds.
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If you are worried about availability of your node when is its turn to
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bake/endorse there are other ways than duplicating your credentials.
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**Never** use the same account on two daemons.
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Docker
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~~~~~~
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The docker image runs the daemons by default for all your keys.
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To know if you baked, just run:
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./alphanet.sh baker log
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./alphanet.sh endorser log
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You should see lines such as:
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::
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Injected block BLxzbB7PBW1axq for bootstrap5 after BLSrg4dXzL2aqq (level 1381, slot 0, fitness 00::0000000000005441, operations 21)
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Or:
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::
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Injected endorsement for block 'BLSrg4dXzL2aqq' (level 1381, slot 3, contract bootstrap5) 'oo524wKiEWBoPD'
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