# CrateDB cluster using docker doesn't form **URL:** \ **Category:** CrateDB\ **Created:** [June 6, 2023, 7:17am UTC](https://community.cratedb.com/t/cratedb-cluster-using-docker-doesnt-form/1507 "2023-06-06T07:17:21Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![cocoa](https://sea2.discourse-cdn.com/flex020/user_avatar/community.cratedb.com/cocoa/32/783_2.png) [@cocoa](https://community.cratedb.com/u/cocoa)\ **Post date:** [June 6, 2023, 7:17am UTC](https://community.cratedb.com/t/cratedb-cluster-using-docker-doesnt-form/1507/1 "2023-06-06T07:17:21Z")
Hello, I’m trying to build a CrateDB cluster using docker and the host type network, to use the subnet where the three host machines are connected. I use these commands, each on a single host: host1 `docker run -d --name crate1 --net=host --env CRATE_HEAP_SIZE=2g --env CRATE_CLUSTER_NAME=my_cluster --env CRATE_DISCOVERY_SEEDS=10.0.0.2,10.0.0.3 crate` host2 `docker run -d --name crate2 --net=host --env CRATE_HEAP_SIZE=2g --env CRATE_CLUSTER_NAME=my_cluster --env CRATE_DISCOVERY_SEEDS=10.0.0.1,10.0.0.3 crate` host3 `docker run -d --name crate3 --net=host --env CRATE_HEAP_SIZE=2g --env CRATE_CLUSTER_NAME=my_cluster --env CRATE_DISCOVERY_SEEDS=10.0.0.1,10.0.0.2 crate` I’m trying to build a CrateDB cluster using docker and the host type network, to use the subnet where the three host machines are connected. I use these commands, each on a single host, three instances of cratedb are created but all as master and no cluster is formed. Do you have a suggestion of how to create the cluster in this way (docker with --net host)? Thank you. Luca ---
**Author:** ![hernanc](https://sea2.discourse-cdn.com/flex020/user_avatar/community.cratedb.com/hernanc/32/676_2.png) [@hernanc](https://community.cratedb.com/u/hernanc)\ **Post date:** [June 6, 2023, 8:54am UTC](https://community.cratedb.com/t/cratedb-cluster-using-docker-doesnt-form/1507/2 "2023-06-06T08:54:14Z")
Hi, You would need to change your commands into something like: ```bash docker run -d --name crate1 --net=host --env CRATE_HEAP_SIZE=2g crate -Ccluster.name=my_cluster -Cdiscovery.seed_hosts=10.0.0.2,10.0.0.3 -Ccluster.initial_master_nodes=10.0.0.1,10.0.0.2,10.0.0.3 docker run -d --name crate2 --net=host --env CRATE_HEAP_SIZE=2g crate -Ccluster.name=my_cluster -Cdiscovery.seed_hosts=10.0.0.1,10.0.0.3 -Ccluster.initial_master_nodes=10.0.0.1,10.0.0.2,10.0.0.3 docker run -d --name crate3 --net=host --env CRATE_HEAP_SIZE=2g crate -Ccluster.name=my_cluster -Cdiscovery.seed_hosts=10.0.0.1,10.0.0.2 -Ccluster.initial_master_nodes=10.0.0.1,10.0.0.2,10.0.0.3 ``` Please note that for security reasons you should configure your network so that the CrateDB cluster nodes are only reachable on port 4300 from other CrateDB nodes in the cluster. ---
**Author:** ![cocoa](https://sea2.discourse-cdn.com/flex020/user_avatar/community.cratedb.com/cocoa/32/783_2.png) [@cocoa](https://community.cratedb.com/u/cocoa)\ **Post date:** [June 6, 2023, 3:57pm UTC](https://community.cratedb.com/t/cratedb-cluster-using-docker-doesnt-form/1507/3 "2023-06-06T15:57:10Z")
Hi hernanc, thank you, your answer solved the situation. The cluster is formed. Now I’ve two critical error , `The value of the cluster setting 'gateway.expected_data_nodes' (or the deprecated `gateway.recovery\_after\_nodes` setting)must be equal to the maximum/expected number of (data) nodes in the cluster. https://cr8.is/d-node-check-1` `The value of the cluster setting 'gateway.recover_after_data_nodes' (or the deprecated `gateway.recovery\_after\_nodes` setting)needs to be greater than half of the maximum/expected number of (data) nodes and equal or less than the maximum/expected number of (data) nodes in the cluster. https://cr8.is/d-node-check-2` Is it correct to set ```auto gateway.expected_data_nodes = 3 gateway.recover_after_data_nodes = 2 ``` with these values ? Thx. Luca ---
**Author:** ![hernanc](https://sea2.discourse-cdn.com/flex020/user_avatar/community.cratedb.com/hernanc/32/676_2.png) [@hernanc](https://community.cratedb.com/u/hernanc)\ **Post date:** [June 6, 2023, 4:02pm UTC](https://community.cratedb.com/t/cratedb-cluster-using-docker-doesnt-form/1507/4 "2023-06-06T16:02:16Z")
Hi, Glad that it worked. With those settings you mention the warnings should disappear, but there are implications to configure `recover_after_data_nodes` to a value lower than `expected_data_nodes`. In 5.4 we are improving the wording around those warnings and the documentation, you can read more about what these mean in the updated documentation which you can reach at this link [System information — CrateDB: Reference](https://crate.io/docs/crate/reference/en/master/admin/system-information.html#recovery-expected-nodes) ---
**Author:** ![cocoa](https://sea2.discourse-cdn.com/flex020/user_avatar/community.cratedb.com/cocoa/32/783_2.png) [@cocoa](https://community.cratedb.com/u/cocoa)\ **Post date:** [June 6, 2023, 4:51pm UTC](https://community.cratedb.com/t/cratedb-cluster-using-docker-doesnt-form/1507/5 "2023-06-06T16:51:29Z")
Hi, What’s your suggestion for a correct setting of the cluster ? Thx, Luca