Use Docker and Flextesa to Run an Independent Tezos Sandbox

Running ephemeral and isolated sandboxes can be useful to experiment with faster networks or to automate reproducible tests.
Here we use Flextesa to run one or more Tezos nodes, bakers, and endorsers contained in a sandbox environment. The default sandbox is configured to be compatible with the tezos-client installed in the “Client-setup” section.


This example requires Docker, available for Linux, Mac or Windows at

Starting and Using a Sandbox

Start the sandbox in the background (will run with baking enabled):
docker run --rm --name my-sandbox --detach -p 20000:20000 \
tqtezos/flextesa:20210602 flobox start
After a few seconds this should succeed:
tezos-client config reset # Cleans-up left-over configuration.
tezos-client --endpoint http://localhost:20000 bootstrapped
Configure the client to communicate with the sandbox:
tezos-client --endpoint http://localhost:20000 config update
Then, instead of using a public faucet one can just use ꜩ by importing accounts already existing in the sandbox. They are visible with:
$ docker run --rm tqtezos/flextesa:20210602 flobox info
Usable accounts:
- alice
* edpkvGfYw3LyB1UcCahKQk4rF2tvbMUk8GFiTuMjL75uGXrpvKXhjn
* tz1VSUr8wwNhLAzempoch5d6hLRiTh8Cjcjb
* unencrypted:edsk3QoqBuvdamxouPhin7swCvkQNgq4jP5KZPbwWNnwdZpSpJiEbq
- bob
* edpkurPsQ8eUApnLUJ9ZPDvu98E8VNj4KtJa1aZr16Cr5ow5VHKnz4
* tz1aSkwEot3L2kmUvcoxzjMomb9mvBNuzFK6
* unencrypted:edsk3RFfvaFaxbHx8BMtEW1rKQcPtDML3LXjNqMNLCzC3wLC1bWbAt
Root path (logs, chain data, etc.): /tmp/mini-box (inside container).
You may then just import them:
tezos-client import secret key alice unencrypted:edsk3QoqBuvdamxouPhin7swCvkQNgq4jP5KZPbwWNnwdZpSpJiEbq --force
tezos-client import secret key bob unencrypted:edsk3RFfvaFaxbHx8BMtEW1rKQcPtDML3LXjNqMNLCzC3wLC1bWbAt --force
Check their balances:
tezos-client get balance for alice

Using The Sandbox

See also the Tezos Client section or the Wallet-usage tutorial of the Tezos manual.
For instance, one can originate the most minimalistic contract:
# Download the contract:
# Run origination:
tezos-client originate contract hello-id transferring 0 from bob running --init "\"hello world\"" --burn-cap 1 --force

Shutting Down The Sandbox

When you're done playing, just destroy the container:
docker kill my-sandbox

Advanced Usage

Tweak Protocol Constants

One can see the configuration of the protocol running in the sandbox with:
tezos-client rpc get /chains/main/blocks/head/context/constants
One important field is "time_between_blocks": [ "5" ], which means that blocks are baked every 5 seconds (as opposed to 60 seconds on Mainnet).
This constant can be configured with the block_time environment variable, see example below:
docker run --rm --name my-sandbox -e block_time=2 --detach -p 20000:20000 \
tqtezos/flextesa:20210602 flobox start
The above command runs a full sandbox with the Florence protocol and a faster time-between-blocks of 2 seconds.
Many other parameters are set by the flobox script. All the configuration options available can be seen with the command:
docker run --rm -it tqtezos/flextesa:20210602 flextesarl mini-net --help

Try The Granada Protocol

The Docker image also contains a granabox script:
docker run --rm --name my-sandbox --detach -p 20000:20000 \
tqtezos/flextesa:20210602 granabox start
On can then check that the protocol hash is PtGRANADsDU8R9daYKAgWnQYAJ64omN1o3KMGVCykShA97vQbvV:
$ tezos-client rpc get /chains/main/blocks/head/metadata | grep protocol
{ "protocol": "PtGRANADsDU8R9daYKAgWnQYAJ64omN1o3KMGVCykShA97vQbvV",
"next_protocol": "PtGRANADsDU8R9daYKAgWnQYAJ64omN1o3KMGVCykShA97vQbvV",
or that there are new constants like the one related to liquidity baking:
$ tezos-client rpc get /chains/main/blocks/head/context/constants | grep liquidity
"liquidity_baking_subsidy": "2500000",
"liquidity_baking_sunset_level": 525600,
"liquidity_baking_escape_ema_threshold": 1000000 }

Further Reading

For more issues or questions, see the Flextesa repository, and for even more advanced usage, see the documentation (esp. for the mini-net command).