Add support for environment variable secrets

Env var secrets are env vars that are set inside the container but not
commited to and image. Also support reading from env var when creating a
secret.

Signed-off-by: Ashley Cui <acui@redhat.com>

3 files changed, 26 insertions, 12 deletions

diff --git a/docs/source/markdown/podman-create.1.md b/docs/source/markdown/podman-create.1.md
index 229bb82f5..7e1d0be4a 100644
--- a/docs/source/markdown/podman-create.1.md
+++ b/docs/source/markdown/podman-create.1.md
@@ -840,7 +840,7 @@ Specify the policy to select the seccomp profile. If set to *image*, Podman will
 
 Note that this feature is experimental and may change in the future.
 
-#### **\-\-secret**=*secret*
+#### **\-\-secret**=*secret*[,opt=opt ...]
 
 Give the container access to a secret. Can be specified multiple times.
 
@@ -848,12 +848,17 @@ A secret is a blob of sensitive data which a container needs at runtime but
 should not be stored in the image or in source control, such as usernames and passwords,
 TLS certificates and keys, SSH keys or other important generic strings or binary content (up to 500 kb in size).
 
-Secrets are copied and mounted into the container when a container is created. If a secret is deleted using
-`podman secret rm`, the container will still have access to the secret. If a secret is deleted and
-another secret is created with the same name, the secret inside the container will not change; the old
-secret value will still remain.
+When secrets are specified as type `mount`, the secrets are copied and mounted into the container when a container is created.
+When secrets are specified as type `env`, the secret will be set as an environment variable within the container.
+Secrets are written in the container at the time of container creation, and modifying the secret using `podman secret` commands
+after the container is created will not affect the secret inside the container.
 
-Secrets are managed using the `podman secret` command.
+Secrets and its storage are managed using the `podman secret` command.
+
+Secret Options
+
+- `type=mount|env`    : How the secret will be exposed to the container. Default mount.
+- `target=target`     : Target of secret. Defauts to secret name.
 
 #### **\-\-security-opt**=*option*
 
diff --git a/docs/source/markdown/podman-run.1.md b/docs/source/markdown/podman-run.1.md
index 2e6d97a05..56ca8fde0 100644
--- a/docs/source/markdown/podman-run.1.md
+++ b/docs/source/markdown/podman-run.1.md
@@ -892,7 +892,7 @@ Specify the policy to select the seccomp profile. If set to *image*, Podman will
 
 Note that this feature is experimental and may change in the future.
 
-#### **\-\-secret**=*secret*
+#### **\-\-secret**=*secret*[,opt=opt ...]
 
 Give the container access to a secret. Can be specified multiple times.
 
@@ -900,12 +900,17 @@ A secret is a blob of sensitive data which a container needs at runtime but
 should not be stored in the image or in source control, such as usernames and passwords,
 TLS certificates and keys, SSH keys or other important generic strings or binary content (up to 500 kb in size).
 
-Secrets are copied and mounted into the container when a container is created. If a secret is deleted using
-`podman secret rm`, the container will still have access to the secret. If a secret is deleted and
-another secret is created with the same name, the secret inside the container will not change; the old
-secret value will still remain.
+When secrets are specified as type `mount`, the secrets are copied and mounted into the container when a container is created.
+When secrets are specified as type `env`, the secret will be set as an environment variable within the container.
+Secrets are written in the container at the time of container creation, and modifying the secret using `podman secret` commands
+after the container is created will not affect the secret inside the container.
 
-Secrets are managed using the `podman secret` command
+Secrets and its storage are managed using the `podman secret` command.
+
+Secret Options
+
+- `type=mount|env`    : How the secret will be exposed to the container. Default mount.
+- `target=target`     : Target of secret. Defauts to secret name.
 
 #### **\-\-security-opt**=*option*
 
diff --git a/docs/source/markdown/podman-secret-create.1.md b/docs/source/markdown/podman-secret-create.1.md
index f5a97a0f3..7aacca3fe 100644
--- a/docs/source/markdown/podman-secret-create.1.md
+++ b/docs/source/markdown/podman-secret-create.1.md
@@ -20,6 +20,10 @@ Secrets will not be committed to an image with `podman commit`, and will not be
 
 ## OPTIONS
 
+#### **\-\-env**=*false*
+
+Read secret data from environment variable
+
 #### **\-\-driver**=*driver*
 
 Specify the secret driver (default **file**, which is unencrypted).