kubectl apply vs kubectl create?

Question

What I understood by the documentation is that:

• kubectl create = Creates a new k8s resource in the cluster
• kubectl replace

Answer 1

These are imperative commands :

kubectl run = kubectl create deployment

Advantages:

• Simple, easy to learn and easy to remember.
• Require only a single step to make changes to the cluster.

Disadvantages:

• Do not integrate with change review processes.
• Do not provide an audit trail associated with changes.
• Do not provide a source of records except for what is live.
• Do not provide a template for creating new objects.

These are imperative object config:

kubectl create -f your-object-config.yaml

kubectl delete -f your-object-config.yaml

kubectl replace -f your-object-config.yaml

Advantages compared to imperative commands:

• Can be stored in a source control system such as Git.
• Can integrate with processes such as reviewing changes before push and audit trails.
• Provides a template for creating new objects.

Disadvantages compared to imperative commands:

• Requires basic understanding of the object schema.
• Requires the additional step of writing a YAML file.

Advantages compared to declarative object config:

• Simpler and easier to understand.
• More mature after Kubernetes version 1.5.

Disadvantages compared to declarative object configuration:

• Works best on files, not directories.
• Updates to live objects must be reflected in configuration files, or they will be lost during the next replacement.

These are declarative object config

kubectl diff -f configs/

kubectl apply -f configs/

Advantages compared to imperative object config:

• Changes made directly to live objects are retained, even if they are not merged back into the configuration files.
• Better support for operating on directories and automatically detecting operation types (create, patch, delete) per-object.

Disadvantages compared to imperative object configuration:

• Harder to debug and understand results when they are unexpected.
• Partial updates using diffs create complex merge and patch operations.