constraints

An array of constraint expressions to limit the set of nodes where a task can be scheduled. Constraint expressions can either use a match (==) or exclude (!=) rule. Multiple constraints find nodes that satisfy every expression (AND match). Constraints can match node or Docker Engine labels as follows: node attribute | matches | example ---------------------|--------------------------------|----------------------------------------------- node.id | Node ID | node.id==2ivku8v2gvtg4 node.hostname | Node hostname | node.hostname!=node-2 node.role | Node role (manager/worker) | node.role==manager node.platform.os | Node operating system | node.platform.os==windows node.platform.arch | Node architecture | node.platform.arch==x86_64 node.labels | User-defined node labels | node.labels.security==high engine.labels | Docker Engine's labels | engine.labels.operatingsystem==ubuntu-24.04 engine.labels apply to Docker Engine labels like operating system, drivers, etc. Swarm administrators add node.labels for operational purposes by using the #operation/NodeUpdate.