Flextesa: Flexible Tezos Sandboxes

This repository contains the Flextesa library used in tezos/tezos to build the tezos-sandbox tests, as well as some extra testing utilities, such as the flextesa application, which may be useful to the greater community (e.g. to test third party tools against fully functional Tezos sandboxes).

Run With Docker

The current released image is oxheadalpha/flextesa:20221123 (also available as oxheadalpha/flextesa:latest):

It is built top of the flextesa executable and Octez suite, for 2 architectures: linux/amd64 and linux/arm64/v8 (tested on Apple Silicon); it also contains the *box scripts to quickly start networks with predefined parameters. For instance:

docker run --rm --name my-sandbox --detach -p 20000:20000 \
       -e block_time=3 \
       "$image" "$script" start

All the available scripts start single-node full-sandboxes (i.e. there is a baker advancing the blockchain):

The default block_time is 5 seconds.

See also the accounts available by default:

$ docker exec my-sandbox $script info
Usable accounts:

- alice
  * edpkvGfYw3LyB1UcCahKQk4rF2tvbMUk8GFiTuMjL75uGXrpvKXhjn
  * tz1VSUr8wwNhLAzempoch5d6hLRiTh8Cjcjb
  * unencrypted:edsk3QoqBuvdamxouPhin7swCvkQNgq4jP5KZPbwWNnwdZpSpJiEbq
- bob
  * edpkurPsQ8eUApnLUJ9ZPDvu98E8VNj4KtJa1aZr16Cr5ow5VHKnz4
  * tz1aSkwEot3L2kmUvcoxzjMomb9mvBNuzFK6
  * unencrypted:edsk3RFfvaFaxbHx8BMtEW1rKQcPtDML3LXjNqMNLCzC3wLC1bWbAt

Root path (logs, chain data, etc.): /tmp/mini-box (inside container).

The implementation for these scripts is src/scripts/tutorial-box.sh, they are just calls to flextesa mini-net (see its general documentation).

The scripts run sandboxes with archive nodes for which the RPC port is 20 000. You can use any client, including the octez-client inside the docker container, which happens to be already configured:

$ alias tcli='docker exec my-sandbox octez-client'
$ tcli get balance for alice
2000000 ꜩ

You can always stop the sandbox, and clean-up your resources with: docker kill my-sandbox.


The scripts inherit the mini-net's support for user-activated-upgrades (a.k.a. “hard forks”). For instance, this command starts a Kathmandu sandbox which switches to Lima at level 20:

$ docker run --rm --name my-sandbox --detach -p 20000:20000 \
         -e block_time=2 \
         "$image" kathmandubox start --hard-fork 20:Lima:

With tcli above and jq you can keep checking the following to observe the protocol change:

$ tcli rpc get /chains/main/blocks/head/metadata | jq .level_info,.protocol
  "level": 24,
  "level_position": 23,
  "cycle": 2,
  "cycle_position": 7,
  "expected_commitment": true


Full Governance Upgrade

The start_upgrade command is included with the docker image.

This implementation of src/scripts/tutorial-box.sh is a call to flextesa daemons-upgrade (see its general daemons-upgrade).

$ docker run --rm --name my-sandbox -p 20000:20000 --detach \
         -e block_time=2 \
         "$image" kathmandubox start_upgrade

With start_upgrade the sandbox network will do a full voting round followed by a protocol change. The kathmandubox script will start with the Kathmandu protocol and upgrade to Lima; the limabox upgrades to to Alpha.

Voting occurs over five periods. You can adjust the length of the voting periods with the variable blocks_per_voting_period. Batches of dummy proposals will be inserted with extra_dummy_proposals_batch_size. These proposals can be scheduled at specific block-levels within the first (Proposal) voting period, using the variable extra_dummy_proposals_batch_level.

$ docker run --rm --name my-sandbox -p 20000:20000 --detach \
         -e blocks_per_voting_period=12 \
         -e extra_dummy_proposals_batch_size=2 \
         -e extra_dummy_proposals_batch_level=2,4 \
         -e number_of_bootstrap_accounts=2
         "$image" kathmandubox start_upgrade

The above command will result in 5 total proposals and upgrade to the Alpha proposal. As of the Lima protocol, the extra_dummy_proposals_batch_size can't exceed the number_of_bootstrap_accounts or the operations will fail with too many manager_operations_per_block.

The default values are:

Note: As with the start command start_upgrade comes with the Alice and Bob accounts by default.

Transaction Optimistic Rollups

The start_toru command included in the scripts is and implementation of the flextesa mini-network with the addition of the option --tx-rollup 10:torubox.

$ docker run --rm --name my-sandbox --detach -p 20000:20000 \
       "$image" "$script" start_toru

After starting up the mini-network, Flextesa will originate a transaction optimistic rollup called tourbox at bock level 10 and start a transaction rollup operator node. Like the scripts above, the Alice and Bob account will be included by default.

Before you can interact with the transaction rollup, you will need to retrieve some important information with the following command.

$ docker exec my-sandbox ${script} toru_info
  "data_dir": "/tmp/mini-box/tx-rollup-torubox/torubox-operator-node-000/data-dir",
  "rollup_id": "txr1arPn95HNJ2JPxFL1q51LGgk4KeR4v36p8",
  "rpc_port": "",
  "mode": "operator",
  "signers": {
    "operator": "tz1db9qaMMNoQPAATe2D3kafKzWWNuMhnmbT",
    "submit_batch": "tz1YVgxuvoqc2DxLjMcmgcpgnWXn6wiJNf5E",
    "finalize_commitment": "tz1WbzTV5WrHBbfbc8Bw55xaQWLjNvfcBKp4",
    "remove_commitment": "tz1ihyGvQHQu1F6TVMqKJdPtw2BHqMcDotsT",
    "rejection": "tz1gDMHL96KSohLp2H5RPFxAM7wATD7zffRV",
    "dispatch_withdrawals": "tz1LuLiAjZs2sFgivjsuLiuB8nJA48pVfcQc"
  "allow_deposit": true
    "name": "torubox-deposit-contract",
    "value": "KT1NjJEFRjAugzPwAkEccTAq3v2SYoScyGnL"

For the next few examples we will record the rollup_id, rpc_addr and the KT1 address for the torubox-deposit-contract. (We continue with tcli alias created above.)

$ rollup_id=txr1arPn95HNJ2JPxFL1q51LGgk4KeR4v36p8
$ rpc_port=20002
$ contract=KT1NjJEFRjAugzPwAkEccTAq3v2SYoScyGnL

Next create a tz4 transaction rollup address and transfer tickets to that address on the rollup via the torubox-deposit-contract:

$ tcli bls gen keys rollup_bob
$ tcli bls show address rollup_bob
Hash: tz4EimhLzauGZjt6ebLDzbD9Dfuk9vwj7HUz
Public Key: BLpk1x8Eu1D5DWnop7osZtDx8kkBgG83tFiNcyBKkFatUg1wKpVbmjY2QqJehfju1t7YydXidXhF

$ bobs_tz4=tz4EimhLzauGZjt6ebLDzbD9Dfuk9vwj7HUz

$ tcli transfer 0 from alice to "$contract" \
        --arg "(Pair \"my_tickts\" 100 \"${bobs_tz4}\" \"${rollup_id}\")" \
        --burn-cap 1

The above argument passed to the contract's default entrypoint will send 100 tickets containing the string "my_tickets" to rollup_bob's address on the TORU. A successful transfer will produces a long out put. For this example, we are interested in the ticket.

e.g. Ticket hash: exprtp67k3xjvBWX4jBV4skJFNDYVp4XKJKujG5vs7SvkF9h9FSxtP

Use the ticket hash to check the balance of the roll_bob with the tx-rollup-client. As with the octez-client, you can use the rollup-client configured inside of the docker container. For example:

$ ticket_hash=exprtp67k3xjvBWX4jBV4skJFNDYVp4XKJKujG5vs7SvkF9h9FSxtP
$ alias torucli='docker exec my-sandbox tezos-tx-rollup-client-014-PtKathma -E http://localhost:${rpc_port}'

$ torucli get balance for rollup_bob of "$ticket_hash"

Note that the transaction rollup client should use the RPC address of the transaction rollup node.


With Opam ≥ 2.1:

opam switch create . --deps-only \
     --formula='"ocaml-base-compiler" {>= "4.13" & < "4.14"}'
eval $(opam env)
opam pin add -n tezai-base58-digest https://gitlab.com/oxheadalpha/tezai-base58-digest.git
opam install --deps-only --with-test --with-doc \
     ./tezai-tz1-crypto.opam \
     ./flextesa.opam ./flextesa-cli.opam # Most of this should be already done.
opam install merlin ocamlformat.0.24.1    # For development.



The above builds the flextesa library, the flextesa command line application (see ./flextesa --help) and the tests (in src/test).

MacOSX Users

At runtime, sandboxes usually depend on a couple of linux utilities.

If you are on Mac OS X, you can do brew install coreutils util-linux. Then run the tests with:

export PATH="/usr/local/opt/coreutils/libexec/gnubin:/usr/local/opt/util-linux/bin:$PATH"

Build Of The Docker Image

See ./Dockerfile, it often requires modifications with each new version of Octez or for new protocols, the version of the Octez static binaries (x86_64 and arm64) is set in src/scripts/get-octez-static-binaries.sh.

There are 2 images: -build (all dependencies) and -run (stripped down image with only runtime requirements).

The x86_64 images are built by the CI, see the job docker:images: in ./.gitlab-ci.yml.

To build locally:

docker build --target build_step -t flextesa-build .
docker build --target run_image -t flextesa-run .

Do not forget to test it: docker run -it "$image" limabox start

Multi-Architecture Image

To build the released multi-architecture images, we used to use buildx but this does not work anymore (Qemu cannot handle the build on the foreign archtecture). We use the “manifest method” cf. docker.com. We need one host for each architecture (AMD64 and ARM64).

On Each Architechture

Setting up Docker (example of AWS-like Ubuntu hosts):

sudo apt update
sudo apt install docker.io
sudo adduser ubuntu docker

(may have to sudo su ubuntu to really get into the group)

Build and push the image (you may need to docker login):

docker build --target run_image -t flextesa-run .
docker tag flextesa-run "$base:$tag-$(uname -p)"
docker push "$base:$tag-$(uname -p)"

Merging The Manifests

On any host:

docker manifest create $base:$tag \
      --amend $base:$tag-aarch64 \
      --amend $base:$tag-x86_64
docker manifest push $base:$tag

When ready for the release, repeat the theses steps swapping the manifest "$tag" each time. Once sans "-rc" and again for "latest".

docker manifest create $base:$newtag \
      --amend $base:$tag-aarch64 \
      --amend $base:$tag-x86_64
docker manifest push $base:$newtag
docker manifest create $base:latest \
      --amend $base:$tag-aarch64 \
      --amend $base:$tag-x86_64
docker manifest push $base:latest

More Documentation

The command flextesa mini-net [...] has a dedicated documentation page: The mini-net Command.

Documentation regarding flextesa daemons-upgrade [...] can be found here: The daemons-upgrade Command.

The API documentation of the Flextesa OCaml library starts here: Flextesa: API.

Some documentation, including many examples, is part of the tezos/tezos repository: Flexible Network Sandboxes (it uses the tezos-sandbox executable which is implemented there).

Blog posts:

TQ Tezos' Digital Assets on Tezos documentation shows how to quickly set up a docker sandbox (uses the docker images from this repository).