Seamless migration of containers between host nodes

A computer system comprising:

• a processor set;
• one or more computer-readable storage media;
• and
• program instructions stored on the one or more computer-readable storage media to cause the processor set to perform operations comprising:
• receiving an indication that a checkpointed state of a container running an application providing at least one of a set of critical services or a set of non-critical services was transferred from a source host node to a target host node, wherein the checkpointed state comprises active network connections of the container and a transmission control protocol (TCP)/IP stack of the container stored in memory;
• and
• responsive to receiving the indication, directing a migration helper located on the target host node to restore and run the container running the application providing the at least one of the set of critical services or the set of non-critical services on the target host node without interruption of the set of critical services based on the checkpointed state of the container transferred from the source host node and an internal IP address of the container that did not change during migration to the target host node, such that remote endpoints of the active network connections do not experience a connection interruption during migration to the target host node;
• wherein the container includes the internal IP address that does not change during migration and an external floating IP address that is a network-layer address assigned by a container network interface (CNI) plugin of a container orchestration environment in accordance with a CNI standard, the external floating IP address changing during migration from the source host node to the target host node.

A computer program product comprising:

• one or more computer-readable storage media;
• and
• program instructions stored on the one or more computer-readable storage media to perform operations comprising:
• receiving an indication that a checkpointed state of a container running an application providing at least one of a set of critical services or a set of non-critical services was transferred from a source host node to a target host node, wherein the checkpointed state comprises active network connections of the container and a transmission control protocol (TCP)/IP stack of the container stored in memory;
• and
• responsive to receiving the indication, directing a migration helper located on the target host node to restore and run the container running the application providing the at least one of the set of critical services or the set of non-critical services on the target host node without interruption of the set of critical services based on the checkpointed state of the container transferred from the source host node and an internal IP address of the container that did not change during migration to the target host node, such that remote endpoints of the active network connections do not experience a connection interruption during migration to the target host node;
• wherein the container includes the internal IP address that does not change during migration and an external floating IP address that is a network-layer address assigned by a container network interface (CNI) plugin of a container orchestration environment in accordance with a CNI standard, the external floating IP address changing during migration from the source host node to the target host node.