Christopher Bouhadi, 25, left Barry Fleming, 28, dying in a pool of his own blood after the incident in Broxburn, West Lothian last May .
Bouhadi – an infantryman in the Black Watch for eight months before being thrown out for failing drug tests – stabbed Mr Fleming in the neck with a knife before running off and hiding the foot-long murder weapon in a bin.
The incident happened outside the Clifton Arms pub in Broxburn, West Lothian around 9pm on 29 May last year.
The High Court in Livingston heard that Bouhadihad guzzled "two mugs of raspberry vodka and two mugs of red wine" to wash down four Valium tablets on the night of the murder.
Judge Lord Philip ordered him to serve a minimum of 16 years in jail before being eligible for parole.
Lord Philip praised Lara Turnbull, 20, a nursery nurse, who ran over after the incident and tried to save Mr Fleming's life.
The judge said she had acted "without any thought for her own safety".
Elizabeth Reynolds, 43, who worked in the Drinkers Paradise off-licence, said that Bouhadi came into the shop moments after he had stabbed his friend and bragged about it.
John Clark, 58, a forensic pathologist at Glasgow University, said Mr Fleming had bled internally, and that he "couldn't have been saved".
Solicitor general Frank Mulholland QC, prosecuting, said that Bouhadi had shown "no remorse or concern for his only friend" after committing the "horrendous crime".
He added that Bouhadi had "tried to con police that he is mentally ill. His approach to this is 'poor me, poor me, poor me'."
Bouhadi had pleaded not guilty to murder.