const char *flux_attr_get (flux_t *h, const char *name);
int flux_attr_set (flux_t *h, const char *name, const char *val);
Flux broker attributes are both a simple, general-purpose key-value store with scope limited to the local broker rank, and a method for the broker to export information needed by Flux services and utilities.
flux_attr_get() retrieves the value of the attribute name.
Attributes that have the broker tags as immutable are cached automatically in the flux_t handle. For example, the "rank" attribute is a frequently accessed attribute whose value never changes. It will be cached on the first access and thereafter does not require an RPC to the broker to access.
flux_attr_set() updates the value of attribute name to val.
If name is not currently a valid attribute, it is created.
If val is NULL, the attribute is unset.
flux_attr_get() returns the requested value on success. On error, NULL
is returned and errno is set appropriately.
flux_attr_set() returns zero on success. On error, -1 is returned
and errno is set appropriately.
The requested attribute is invalid or has a NULL value on the broker.
Some arguments were invalid.
Set was attempted on an attribute that is not writable with the user's credentials.