The application for the writ of habeas corpus shall be by petition in writing, signed by the applicant, his attorney or agent, or some other person in his behalf, and shall state:

(1) The name or description of the person whose liberty is restrained;

(2) The person restraining, the mode of restraint, and the place of detention as nearly as practicable;

(3) The cause or pretense of the restraint. If the restraint is under the pretext of legal process, a copy of the process must be annexed to the petition if this is within the power of the applicant;

(4) A distinct averment of the alleged illegality in the restraint or of any other reason why the writ of habeas corpus is sought; and

(5) A prayer for the writ of habeas corpus.