Add documentation of how to use the program in README
I spent some time to understand this process while testing mTLS on
bmcweb.
Having some extra documentation should help people new to the community.
Signed-off-by: Zhenfei Tai <ztai@google.com>
Change-Id: I636c189b5ab5886726af5ce7ce6d2b19ab68f741
diff --git a/README.md b/README.md
index 17832ca..a1c1db8 100644
--- a/README.md
+++ b/README.md
@@ -13,3 +13,61 @@
To clean the repository run `./bootstrap.sh clean`.
```
+
+## To Run
+Multiple instances of `phosphor-certificate-manager` are usually run on the bmc
+to support management of different types of certificates.
+```
+Usage: ./phosphor-certificate-manager [options]
+Options:
+ --help Print this menu
+ --type certificate type
+ Valid types: client,server,authority
+ --endpoint d-bus endpoint
+ --path certificate file path
+ --unit=<name> Optional systemd unit need to reload
+```
+
+### Https certificate management
+**Purpose:** Server https certificate
+```bash
+./phosphor-certificate-manager --type=server --endpoint=https \
+ --path=/etc/ssl/certs/https/server.pem --unit=bmcweb.service
+```
+
+### CA certificate management
+**Purpose:** Client certificate validation
+```bash
+./phosphor-certificate-manager --type=authority --endpoint=ldap \
+ --path=/etc/ssl/certs/authority --unit=bmcweb.service
+```
+
+### LDAP client certificate management
+**Purpose:** LDAP client certificate validation
+```bash
+./phosphor-certificate-manager --type=client --endpoint=ldap \
+ --path=/etc/nslcd/certs/cert.pem
+```
+
+## D-Bus Interface
+`phosphor-certificate-manager` is an implementation of the D-Bus interface
+defined in [this document](https://github.com/openbmc/phosphor-dbus-interfaces/blob/a3d0c212a1e734a77fbaf11c7561c59e59d514da/xyz/openbmc_project/Certs/README.md).
+
+D-Bus service name is constructed by
+"xyz.openbmc_project.Certs.Manager.{Type}.{Endpoint}"
+and D-Bus object path is constructed by
+"/xyz/openbmc_project/certs/{type}/{endpoint}".
+
+Take https certificate management as an example.
+```bash
+./phosphor-certificate-manager --type=server --endpoint=https \
+ --path=/etc/ssl/certs/https/server.pem --unit=bmcweb.service
+```
+D-Bus service name is "xyz.openbmc_project.Certs.Manager.Server.Https" and
+D-Bus object path is "/xyz/openbmc_project/certs/server/https".
+
+## Usage in openbmc/bmcweb
+OpenBMC [bmcweb](https://github.com/openbmc/bmcweb) exposes various [REST APIs](https://github.com/openbmc/bmcweb/blob/master/redfish-core/lib/certificate_service.hpp)
+for certificate management on the BMC, which leverages functionalities of
+`phosphor-certificate-manager` via D-Bus.
+